Thermal batteries are primary reserve batteries that utilize an electrolyte that, at ambient temperatures, is a nonconductive solid. Thermal batteries are characterized as providing a large amount of energy relative to their volume. These batteries, if hermetically sealed, can be stored for a long period of time (in many instances greater than ten years) without substantial degradation of performance, and can perform without preliminary preparation in many different environments. Thus, thermal batteries are a desirable source of power in a number of different applications. Once activated, a thermal battery supplies electric power to a device for time periods ranging from a few seconds to an hour or longer. No maintenance is required for a thermal battery during storage prior to use, which permits it to be permanently installed in devices that themselves may experience long periods of storage before use. For example, thermal batteries are used in missile systems such as Joint Direct Attack Munition (JDAM), Stinger, Javelin, BAT smart missiles, as well as other systems such as aircraft ejector seats, and sonar buoys.
The configuration of a thermal battery is dictated by mechanical and thermodynamic considerations and is typically a right circular cylinder known as a “cell stack.” Mechanically, since the components are rigid and brittle, the stack is sealed under mechanical pressure for dynamic environment considerations such as shock, vibration, and acceleration.
Thermal batteries contain materials that generally are inert and non-conductive until the battery is activated. Upon activation, the materials become molten and highly conductive. This allows the cathode to interact with the anode. The thermal battery materials are activated by igniting the battery. For example, a mixture of iron powder and potassium perchlorate preferably is used to ignite a battery. Once activated, the battery may continue to perform until the active material is exhausted or until the battery cools below the melting point of the electrolyte.
The typical thermal battery has been constructed using manual techniques. The conventional wisdom has been that many of the tasks could not be performed adequately via automation and machine. However, human error and variability may also result from manual manufacturing techniques. Furthermore, manual processing is typically slow. Moreover, there exists a need for improved testing methods. Thus, additional systems, methods, and devices are needed to facilitate the manufacture of thermal batteries.